Transparent CNT Heaters for Laminated Glass

Abstract

A CNT heater is described comprising, in sequence, a first substrate, an adhesive layer, a protective layer, a CNT network layer, and a second substrate. Resistive heating is generated when a current passes through the CNT layer. The system has been found to provide improved stability and stability.

What is claimed: 
     
         1 . A heater comprising, in sequence, a first substrate, an adhesive layer, a layer comprising a sulfonated tetrafluoroethylene based fluoropolymer-copolymer, a CNT network layer, and a cover layer comprising a protective coating and/or a second substrate; and further comprising a conductor electrically connected to the CNT network layer so that a current can be passed through the CNT layer during operation. 
     
     
         2 . The heater of  claim 1  wherein the cover layer comprises a second substrate. 
     
     
         3 . The heater of any of  claims 1 - 2  wherein the first substrate and the heater are transparent. 
     
     
         4 . The heater of any of  claims 1 - 3  wherein the adhesive layer comprises PVB. 
     
     
         5 . The heater of any of  claims 1 - 4  wherein the conductor comprises a copper braid. 
     
     
         6 . The heater of any of  claims 1 - 5  wherein the first and second substrates each comprise at least one layer comprising borosilicate glass. 
     
     
         7 . The heater of any of  claims 1 - 6  having stability such that, when exposed to ambient conditions for 14 days, there is a 10% or less increase in electrical resistance. 
     
     
         8 . The heater of any of  claims 1 - 7  wherein the CNT network layer comprises a length of at least 12 cm disposed between two electrical leads; wherein the heater has flexibility such that, having stability such that, if subjected to a strain of 6000 microstrain via a four-point bend test according to ASTM D6272A at a strain rate of 0.5 in/min, and released to no strain, there is less than a 5% change in electrical resistance. 
     
     
         9 . The heater of  claim 8  wherein, if subjected to ASTM D6272A, there is a 10% or less, preferably 5% or less, change in resistivity at a deflection of 0.75 inches. 
     
     
         10 . The heater of any of  claims 8 - 9  wherein the first and second substrates comprise fiberglass. 
     
     
         11 . The heater of any of  claims 1 - 10  wherein, if subjected to a strain of 6000 microstrain via a four-point bend test according to ASTM D6272A at a strain rate of 0.5 in/min, and released to no strain, there is less than a 10% change in average optical transmittance over the surface of the heater that has the underlying CNT layer. 
     
     
         12 . A turbine blade or a vehicle window comprising the heater of any of the previous claims. 
     
     
         13 . A defroster structure comprising, in sequence, a transparent substrate, an adhesive layer, a protective interlayer, a CNT network layer, a transparent cover layer, and further defined by a stability such that, when exposed to ambient conditions for 14 days, there is 10% or less increase in electrical resistance. 
     
     
         14 . The defroster structure of  claim 13  wherein the adhesive layer comprises PVB. 
     
     
         15 . A method of making the heater or defroster of any of  claims 1 - 14 , comprising:
 applying a CNT network layer on a first substrate;   applying a protective interlayer onto the CNT network layer;   applying an adhesive layer and second substrate onto the CNT network layer to form a laminate such that the adhesive layer is disposed between the CNT layer and the second substrate;   heating the laminate under vacuum that removes gas generated during the heating to form a heated laminate; and   cooling the heated laminate.   
     
     
         16 . The method of  claim 15  wherein the heating comprises hot pressing the laminate under vacuum that removes gas generated during the hot pressing to form a pressed, heated laminate; and cooling the pressed laminate.